MOTOR IMPRESSIONS \m 



upon the axiom— agreed to by physiologists. ])atlio- 

 logists, and anatomists — that " movements, not muscles, 

 are represented in the cerebral cortex.'' 1 think we might 

 extend this axiom by claiming that only *' pictured 

 movements " are represented in the cortex. 



This axiom in reality teaches a great deal, for the braiu 

 knows nothing of muscles, since the animal is itself 

 ignorant; but for movements it has a vast storehouse, 

 the contents of which are in direct ratio to the animal's 

 own pictured know^ledge of the form and movements nf 

 the different parts of its body. 



We may gain considerable knowledge of the functions 

 of this pictured movement area by the consideration uf 

 the results of experiments, which have been carried out 

 by different investigators, upon a series of animals oi 

 varying zoological position. The movements of the 

 different parts of the body are not carried out hi all 

 animals by the same nervous centres. We will tabulate 

 the experimental findings in order. 



1. If a bird, or a Vertebrate lower than a bird, be 

 deprived of its brain altogether, it can continue the 

 movements of its limbs; a deca])itated fowl is not a 

 paralyzed fowd, for it will continue to run and flap its 

 wings for some time despite the entire loss of its brain. 

 " It is possible to remove the entire cerebrum of a ])ige(in, 

 yet it is capable of flight w^hen thrown into the air an 

 hour later " (Kinnier Wilson). 



2. With a Mammal there is no activity, at all compar- 

 able to this manifestation, in the absence of a brain, but 

 very varying effects are produced in different .Mannnals 

 by removal of the pictured movement area of the cortix. 



3. '* On the day of removal of the cerebral centres for t ho 

 limbs, a rabbit will jump vigorously " (Kinnier Wilson). 



4. If this area is removed in a puppy it does not beeonie 

 paralyzed, and one week afterwards, ^^-hen it has recovered 

 from the operation, it can carry out all the movements 

 proper to a normal dog. 



